The present disclosure relates to, a piezoelectric device applied to, for example, an oscillation device or a vibration gyro sensor and to an electronic apparatus including the same.
As consumer angular velocity sensors, vibration gyro sensors are widely used. The vibration gyro sensor detects an angular velocity in such a manner that the vibrator is vibrated at a predetermined frequency and a Coriolis force generated in the vibrator is detected by a piezoelectric element or the like. The gyro sensor is, for example, installed into an electronic apparatus such as a video camera, a virtual reality apparatus, and a car navigation system, which are utilized as, for example, sensors for shake detection, motion detection, and direction detection, respectively.
For example, Japanese Patent No. 4858662 (hereinafter, referred to as Patent Document 1) describes an angular velocity sensor including an annular frame, a drive part to cause the frame to oscillate within a predetermined plane, and a detection part to detect an angular velocity. The frame has a first set of beams opposed to each other and a second set of beams orthogonal to the first set of beams and opposed to each other. The drive part is constituted of a plurality of piezoelectric elements provided in the beams and causes the frame to oscillate within the predetermined plane in an oscillation mode where, when one of the first and second sets of beams comes closer to each other, the other set separates from each other, and when the one set separates from each other, the other set comes closer to each other. The detection part is constituted of a piezoelectric element capable of detecting, on the basis of an amount of deformation of the frame within the predetermined plane, an angular velocity about an axis perpendicular to the predetermined plane.
A piezoelectric device using a piezoelectric film for a drive unit typically utilizes a piezoelectric property that the piezoelectric film expands and contracts in a direction orthogonal to a voltage application direction. For example, in the angular velocity sensor described in Patent Document 1, the drive unit and the detector each have a lamination structure of a lower electrode layer, a piezoelectric material layer, and an upper electrode layer and are provided on the same surface of a frame.